Write out all relationships between variable from first and second case

Write out second case

Substitute all first case variables into second case

Write second case in terms of first case

The acceleration due to gravity at the Earth's surface is, by

convention, equal to 9.80665 ms-2. (The actual value varies slightly over the surface of the Earth). This quantity is known as g. The following is a list of the gravitational accelerations (in multiples of g) at the surfaces of each of the planets in our solar system:

Mercury

0.376

Venus

0.903

Earth

1

Mars

0.38

Jupiter

2.34

Saturn

1.16

Uranus

1.15

Neptune

1.19

Pluto

0.066

Note:

The "surface" is taken to mean the cloud tops of the gas giants (Jupiter, Saturn, Uranus and Neptune) in the above table.

but we know that mZ=12mE{\displaystyle m_{Z}={\frac {1}{2}}m_{E}} and we know that rZ=14r{\displaystyle r_{Z}={\frac {1}{4}}r} so we could write the equation again and substitute these relationships in: